anonymous
  • anonymous
Simplify the expression twenty-one minus seven times two plus nine. Show your work. Then, show how the solution is affected if addition and subtraction are not applied from left to right.
Mathematics
  • Stacey Warren - Expert brainly.com
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SOLVED
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katieb
  • katieb
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anonymous
  • anonymous
Can someone please help me i've been on this problem forever and i cant seem to figure it out someone please help!?
anonymous
  • anonymous
so do you mean 21-7x2+9?
anonymous
  • anonymous
yes

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More answers

anonymous
  • anonymous
oh ok so did you solve it already and just need help with the second question?
anonymous
  • anonymous
no sadly i need help with everything i did not even start i cant seem to understand it :(
anonymous
  • anonymous
no it's fine! :) do you know PEMDAS? or have you heard of it?
anonymous
  • anonymous
yes i do know what pemdas means please excuse my dear ant sally
anonymous
  • anonymous
yes! :) do you know how to use it when you solve a problem?
anonymous
  • anonymous
yes on some problems not all :o
anonymous
  • anonymous
ok that's fine. so i would first multiply 7x2 then subtract 21 then add 9. The reason why i did not add then subtract which i would usually do, is because the second question says "Then, show how the solution is affected if addition and subtraction are not applied from left to right." so i have to do it exactly from left to right. Then i would do it right to left..... did i confuse you at all?
anonymous
  • anonymous
Nope not at all im understanding :D
anonymous
  • anonymous
oh ok! Great i was so worried i was confusing you not helping you! :) so can you tell me, if you solve the problem from left to right what the answer will be?
anonymous
  • anonymous
the answer will be 2
anonymous
  • anonymous
how did you get 2?
anonymous
  • anonymous
i did how pemdas tells me how to do it i multiplyed then i suptarcted then i added
anonymous
  • anonymous
that's what i did and i got 21-14+9 7+9 16
anonymous
  • anonymous
hmm i must off put something in wrong lets try it again and lets see what i get
anonymous
  • anonymous
ok that's fine just take your time :)
anonymous
  • anonymous
yeah i did put something wrong now that ive done the whole process i got 16 :D
anonymous
  • anonymous
awesome! :) now what you just did was solve the problem from left to right which is right. now you do it from right to left and see if there is a difference.
anonymous
  • anonymous
by doing that you will be able to answer the second question
anonymous
  • anonymous
ok so basically the first part is answering the first part of the question and once i do the second part that will be the the answer to the second part of the question?
anonymous
  • anonymous
yup exactly! because once you multiply 7x2 then you add 9 then subtract 21 from your answer... you will see why you can answer question 2.
anonymous
  • anonymous
okay :o be right back ill be back like in 5 mins
anonymous
  • anonymous
that's fine
anonymous
  • anonymous
ok im back my answer for part 2 was 2
anonymous
  • anonymous
i got -2... this is what i did: 21-7x2+9 21-14+9 21-23 -2
anonymous
  • anonymous
7x2=14 +9 -21
anonymous
  • anonymous
thats what i did
anonymous
  • anonymous
it's 21-23 not 23-21
anonymous
  • anonymous
by changing the positioning of the numbers you can change the answer
anonymous
  • anonymous
lol yeah my teacher said that when your subtracting you need to be careful because if you mix the numbers up it can change your whole answer
anonymous
  • anonymous
yeah it's fine it can get confusing in math! :D lol
anonymous
  • anonymous
haha so is that it theres nothing else to do right?
anonymous
  • anonymous
yeah! so you can answer the second question because you know that by changing the order of how you solve the problem then you are essentially changing your answer as well! :D That's all there is to it! :)
anonymous
  • anonymous
haha omg THANKS DO MUCH you've made my day thanks for helping me understand this :D!!
anonymous
  • anonymous
no it is absolutely fine i'm just glad i actually helped you and didn't confuse you! :D you made my day as well! :) lol
anonymous
  • anonymous
haha :)
anonymous
  • anonymous
:) XD
anonymous
  • anonymous
hey got to go thanks for help me!!! hope we can talk some other time :D
anonymous
  • anonymous
yah totally i would really love that! :D just send me a text or something whenever you see me I usually try to be on openstudy every 2 days or so often! :)
anonymous
  • anonymous
bye! :D
anonymous
  • anonymous
21-7+2=16(from left to right). 21-7+2=12(not from left to right) The answer decreased if you don't do it from left to right.

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